How to test your internet speed accurately

What a speed test actually measures

A speed test measures how fast data moves between your device and a test server. It runs in three phases: latency, download and upload. Latency (ping) is the round-trip time for a small request, download measures how quickly the server can push data to you, and upload measures how quickly you can push data back.

The result depends on the whole path — your device, your Wi-Fi or Ethernet link, your router, your ISP's local exchange, the ISP's backbone, and the test server. That is why a result can be far below the number on your bill, and why the same line can measure very differently at 9am and 9pm.

The five steps for an accurate reading

Follow these in order and you will get a number you can trust and compare against your plan.

• Use a wired Ethernet connection if you have one. Wi-Fi on a crowded 2.4 GHz band routinely costs 30–50% of throughput.
• Pause every other download, cloud backup, streaming session and video call on the same network.
• Close VPNs and proxies. They add encryption overhead and reroute your traffic through a distant server.
• Keep the browser tab in the foreground — most browsers throttle background tabs heavily.
• Run the test twice, about a minute apart. If the two results disagree by more than 10%, something else was using the line.

How to read the four numbers

Download speed is the headline figure and the one your plan is sold on. Upload speed is what you need for video calls, cloud backups and publishing large files — it is typically a fraction of download on cable and DSL. Ping is the delay before data arrives, and it matters far more for gaming and remote desktop than raw bandwidth does. Jitter is the variation in that delay; a steady 40 ms is better for a call than a connection swinging between 10 ms and 90 ms.

Why your result might be lower than your plan

If you are consistently well below your subscribed speed, the cause is usually one of five things: Wi-Fi signal loss, another device saturating the line, an older router that cannot handle gigabit throughput, a shared cable segment that is congested in your area, or a device that is the bottleneck rather than the connection. A wired test on the same line separates the first and last causes immediately.